Kahului, where you most likely landed when you arrived on Maui, is the industrial and commercial center of the island. West of Kahului is Wailuku, the county seat since 1950 and the most charming town in Central Maui, with some good inexpensive restaurants. Outside these towns are attractions ranging from museums and historic sites to gardens.
You can combine sightseeing in Central Maui with some shopping at the Queen Kaahumanu Center, Maui Mall, and Maui Marketplace. This is one of the best areas on the island to stock up on groceries and supplies, thanks to major retailers including Walmart, Kmart, and Costco. Note that grocery prices are much higher than on the mainland.